Fusion events between membranes represent an important category of biological dynamics but the conditions required for controlled fusion events in biological systems have not been defined. We have described fusion of model membranes induced by two basic peptides, apocytochrome c and polylysine, in terms of protein binding, charge requirements and pH dependence. Both proteins promote aggregation and fusion between membranes containing 10% or more negatively charged lipids. The fusion event is pH dependent with maximal rates for a given protein concentration occurring below pH 5.0. Fusion rates are maximal when the charge stoichiometry between lipids and protein is nearly 1:1. Electrostatic binding between two membranes allowing sufficient contact between the bilayers increasing the probability that fusion will occur in response to a trigger such as lowered pH, provides a reasonable model for viral protein triggered fusion events and could apply cellular control processes such as membrane turnover and secretion.